1. Field of the Invention
The present invention relates to an apparatus for producing granular solidified slag from molten blast furnace slag. More particularly the present invention relates to an apparatus for producing solidified granular slag having a high density and uniform quality, useful as a fine aggregate and a road subbase.
2. Description of Prior Art
For the production of granular slag from molten blast furnace slag, which is produced in large amounts during in the blast furnace operation, by blowing a high-pressure gas, such as air and steam, to the molten blast furnace slag, it is conventionally known as shown in FIG. 1 to blow compressed air, inert gas, steam or high-pressure water to molten slag falling down from a trough 4 so as to finely divide the slag and cause the finely divided slag to be carried by the air and then fall into a cooling tank 6, where the slag is solidified, and the solidified slag is recovered by means of a conveyor 7.
However, this conventional system requires a large floor area for the equipment and large size equipment for recovering the granular slag. Further the granular high-temperature slag 1 is subjected to rapid cooling so that the quality of the product is thereby adversely influenced.
Thus, according to the conventional system, the molten blast furnace slag is blown off by high-pressure gas, and the blown slag is immediately subjected to rapid cooling by a rapid cooling agent, such as water, so that the molten slag is not always blown into a granular product. Rather, the production rate of fibrous slag wool is high, and even when a granular slag product is obtained, it is a swollen slag which is porous and has an angular surface, and thus inferior physical properties, particularly strength. Therefore, the product of the conventional system has been considerably limited in its application.
According to another conventional system as shown in FIG. 2, the molten blast furnace slag 1 is spouted into the air by means of a rotary drum 2 and is cooled in the air to obtain small granules of solidified slag, which are caused to fall onto a collection yard 3. In order to produce granular slag efficiently by this system, it is necessary to increase the diameter of the rotary drum 2 or increase the rotational speed thereof. However, this requires a larger area of the collection yard because the increased diameter or rotational speed expand the flying zone of the granular slag, so that the recovery efficiency is very low.
Also there is certain limitation in increasing the centrifugal force of the rotary drum 2 from a practical point of view. Therefore, according to this conventional system, the high-temperature slag is not completely solidified while it is flying through the air and it is very often that the slag granules fuse together even in the collection yard, so that efficient production of granular slag is not achieved.